Reptiles are Ectotherms, that is they heat themselves and regulate their body temperature by means of the environment. They move in and out of hot and cool areas to maintain their preferred temperature. It is therefore important that the vivarium has a suitable temperature gradient for the reptiles to behave naturally. The heater should be placed at one end of the vivarium in a condition that does not heat the whole of the enclosure. In this way the temperature will vary between the hot area near the heater and the cooler areas at ambient temperature.